Distributing system for electric railways.



I c. F. soon. DISTRIBUTING SYSTEM FOR ELECTRIC RAILWAYS.

APPLICATION FILED MAR. 8. I917.

1,295,933. Patented Mar. 4,1919. 8 4 5 z z .L I 1., I /I-- lw'gggfrzo iii/20 2x T A 1'sm 22 %@I I I l I WITNESSES; INVENTOR A1644. 4/ [/Mf/SS 56m UNITED STATES PATENT ornron.

CHARLES E. SCOTT, OF NEW HAVEN, CONNECTICUT, ASSIGNOR'TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

DISTRIBUTING SYSTEM FOR ELECTRIC RAILWAYS.

To all whom it may concern I Be it knownthat I, CHARLES F. Scorr, a citizen of the United States, and a resident of New Haven, in the countyof New Haven and State of Connecticut, have invented a new and useful Improvement in Distributing Systems for Electric Railways, of whlch the following is a s ecification.

My invention re ates to electrical distributing systems and particularly to electrical railway systems that employ alternating currents for propulsion purposes and embody means for minimizing inductive disturbances that are likely to arise from the flow of the ower currents.

More particularly, my invention relates to electric railway systems of the above-indicated character in which the several spaced sub-stations comprise transformer windings by means of which the power currents are supplied to the railway sections immediately adjacent to the sub-stations. The windings of these transformers are so related that the inductive effects arising from the currents supplied to the load are minimized or sub-' stantially neutralized by the inductive effects arising from the return currents. Moreover,

the transformer windings embodied in each sub-station are so combined and interconnected that they may be wound on a common transformer core.

Intelligence-transmission circuits, such as telephone and telegraph circuits, are frequently disposed ad 'acent to an electric railway and are, there ore, subject to inductive disturbances arising from the flow of the propulsion currents in the railway circuit. To minimize the inductive disturbances that are frequently impressed upon adjacent in telligence-transmission circuits and seriously interfere with their satisfactory operatlon, many systems have been heretofore proposed a particular one upon which my present invention is'an an improvement belng disclosed in a copending patent application of A. V. Copley and Chas. LeG. Fortescue,

Serial No. 66,733, filed December 14, 1915,

and assigned to the \Vestinghouse Electric and Manufacturing Company.

In the aforementioned patent application, the system shown contemplates the use of series transformers for inductively interlinking the trolley and feeder conductors of the railway system with each other. It is intended that the feeder conductor and the Specification of Letters Patent.

Patented Mar. 4, 1919.

7 Application filed larch 8, 1917. Serial No. 153,312.

trolley conductor shall be so positioned with respect to an adjacent intelligence-transmission circuit which it is desired to protect against inductive disturbances, that the electromotive forces induced therein by the trolley and feeder currents, shall be substantially completely neutralized. Although the Y trolley and feeder conductors are inductively interlinked, the propulsion currents must, of necessity, flow in certain portions of the track circuit which comprise the rail sections upon which the active loads obtain.

In order to substantially. neutralize the effects of the propulsion currents flowing in the track sections of the system in which no loads obtain, the track circuit is interconnected, through auto-transformers, with the .trolley and feeder conductors in such manner as to conduct the propulsion currents from the track circuit except in those sections in which power is required by the loads. At the same time, neutralizing rents are induced to flow in the local clrcuits established through the load and the transformers at the ends. of the section of the track' circuit in which the load is temporarily situated, These currents are effective in neutralizing or minimizing, to a very large extent, any disturbances that may result from the propulsion currents in the track sections in which the active loads obtain.

An object of my present invention is to providing a distributing system that is similar to the one disclosedz n the above-indicated copending patent" application but which comprises inductively related transformer windings that are so interconnected and interrelated-with one another that they may be combined in a single magnetic structure. Since these transformers are to be placed at intervals in the railway circuit, it is desirable to make them as inexpensive and simple in construction as possible which is best obtained by providing a unitary structure that will occupy only a small amount of installation space, as well as, reduce the first cost of the installation.

For a better understanding of the nature and scope of my invention, reference may be had to the following description and the accompanying drawing in which Figure 1 is a diagrammatic view of an alternating-current railway system embodying a form of my invention; Fig. 2 is a simplified diagram illustrating the system shown in Fig.

1, and Fig. 3 is a diagrammatic View of a single transformer in which all of the power-transformer windings of Fig. 1 are incorporated, thus providing a unitary structure.

The system herein described has for its further object the division of the track and feeder circuits into sections through the use of auto-transformers. The voltage between the feeder and trolley is, for example, 22,000

volts and it is desired to operate the vehicle point at which they are connected to the track circuit, a combination of said transformer coils for a certain distance fromthe track can be made. The system hereinafter described and claimed is ,of the above type and I find that by so eliminating one coil of the transformers I am able to con-v struct the latter in the economical and efficient manner hereinafter set forth.

Referring to Fig. 1, a trolley conductor 1 supplies power to a railway system com prising a track 2 that is divided into a plurality of insulated sections 3 that may, at the same time, be employed as block sections for signaling purposes. A return feeder 4 paralleling the trolley conductor 1 and, preferably, being equally spaced from an intellinencetransmission circuit 5, provides means whereby the propulsion currents may return to a source of power-supply, renre sented as a single-phase alternator 6. One terminal of the alternator 6 is connected to the trolley conductor 1, and the other tenninal is connected to the feeder conductor 4, the full potential of the alternator being impressed across the aforementioned conductors. Insulating joints 7 are inserted at spaced intervals in the trolley conductor 1, similar insulating joints 8 being positioned at corresponding pointsin the feeder conductor 4. For convenience, the insulating joints 7 and- 8 may be placed at points corresponding to the position of insulating joints 9 in the track circuit 2, the latter be-' ing provided in orderthat sections of the track circuit may be employed as local circuits for the electric signaling system.

Series transformers 10, comprising primary windings 12, and secondary windings 11, are provided for each pair of insulating joints 7 and-8 in order to inductively interlink the trolley and feeder conductors with each other. --The primary windings 11 are connected in shunt to the insulating joints 7, and the secondary windings 12 are connected in shunt to the insulating joints 8. Transformer windings are provided on both sides of the insulating joints 7 and 8 in order to electrically interconnect the trolley conductor, the track circuit and the feeder with one another. Between the trolley conductor 1 and. the track circuit 2 are connected a winding 13 of a transformer 14 and a winding 15 of a transformer 16, the windin 15 being connected, by means of a conductor 17, to mid-points 18 of impedance bonds 19. The transformer 14 also comprises a winding 20, and the transformer 16 another winding 21, the windings 20 and 21 being connected between the track circuit and the feeder conductor, as will be hereinafter explained. While the transformer 14 is connected in circuit on one side of the insulating joints 7 and 8, a similar transformer 22 is connected on the other side of the insulating joints, the transformer 16 being common to both transformers 14 and 22. v

From the foregoing, it will be apparent that the trolley conductor 1 is electrically continuous, since the coils 11 bridge the insulating joints 7. The return feeder 4 is likewise continuous, since the coils 12 of the series transformers 10 bridge the insulating joints '8. Again, the windings 13 and 15 of the transformers 14 and 16, respectively, are interconnected between the trolley conductor 1 and the track circuit 2, and windings 20 and 21 of the transformers l4 and 16, respectively, are inserted between the track circuit and the return feeder conductor 4.

When a load obtains in the track section 3, the propulsion currents flow from the track section 3 through the windings 21 and 20 to the return feeder conductor 4, the windings 15 and .13 have oppositelydirected currents induced in them, as will be hereinafter explained, which currents circulate in local circuits formed through the load and the track-section 3 occupied by the load.

The signaling system, one of which is usually employed in connection with a railway system, comprises block sections which, in this instance, are the track sections 3. Each section constitutes a local circuit that is connected to a power circuit 22 by means Inasmuch as this signaling system is old in the art, further explanation thereof is not deemed necessary.

The intelligence-transmissibn circuit 5, shown as a telephone circuit, is disposed in proximity to the trolley conductor 1 and the return feeder 4, and is, therefore, subject to the inductive effects arising from the flow of propulsion currents in the railway system. For the satisfactory operation of the telephone circuit 5, it is essential that the inductive disturbances impressed thereupon be minimized and, to this end, my distributing,

system substantially reduces the flow of induced currents in the telephone circuit that may arise from the flow of'propulsion currents in the railway system, as will be subsequently disclosed. I

In Fig. 2 is shown a simplified form of the system of Fig. 1, the inductive windings of the transformers having the same designations as in Fi 1 but being more suitably'arranged to facilitate in explaining their interrelations. The signaling system has been dispensed with and, as a result, the track circuit 2 is devoid of the impedance bonds 19 of Fig. 1, the track circuit, in this instance, being continuous and comprising two rails.

In this figure also is shown in what man ner the one winding 15 takes the place of those portions of the two auto-transformer coils 13 and 13, which are adjacent to the point where said coils are connected to the track circuit. It will be observed that such a combination and consequent elimination of sumed to be held at a potential midway between that of the trolley conductor 1 and that of the feeder conductor 4 by means of the transformers 14 and 16 which are connected to the track circuit through a bond 19. i

To illustrate the electricalcondit-ions obtaining in the railway system of Figs. 1

and 2 at a certain instant, assume, for villus-1 ,tration only, that a locomotive or train 30 occupies, for an instant, a mid-position on a track section intermediate the two groups of transformers. The propulsion current, which traverse the trolley. and feeder circuits'and the direction of flow of which is represented by the full-line arrows 31, flows along the trolley conductor 1, through the winding 11 of the series transformer 10. along a section of the trolley conductor 1 and a trolley pole 32, to the train 30. At this point, the propulsion current divides equally into two portions that flow along the track circuit in opposite directions, I

since it is presumed that the track circuit 2 constitutes a uniform conductor and the train 30 occupies a mid-position upon the track-section, as mentioned above. Onehalf of the propulsion current flows through the rail bond 19", the winding 21 way system is formed of sections such as this, the current supplied to the load 30 and returning therefrom will be confined to the trolley conductor 1 and the return feeder 4 except in the. railway section that is occupied, for the time, by the load 30. In the track section 3, propulsion current will flow as long as the load 30 occupies this'railway section. It is apparent, therefore, that the propulsion current flowing in the trolley section intermediate the generator 6 and the point A of the system is equal in value, and flows in'a direction opposite, to that of the propulsion current flowing in a corresponding portion of the return feeder 4. Therefore, the inductive effects arising from the flow of the propulsion current over this portion of the system and impressed on the telephone circuit 5, are neutralized.

It becomes necessary, therefore, to neu-- tralize the inductive effects arising from the flow of the propulsion current in the portion of the railway system. or that section occupied temporarily by the.load 30 and extending between the two groups of transformers shown in Figs. 1 and 2.

Under the conditions assumedv and as mentioned. above, one-half of the propulsion current flows through the winding 21 and the winding 20 of the transformers 16 and 14, respectively. Equal and oppositely directed currents are, therefore, induced in the winding 15 and in the winding 13 which are mutually inductively related to the windings 21 and 20, respectively. The direction of flow of this induced current is represented by the broken line arrows 32. A local circuit in this railway section occupied by the load 30 is consequently established over which an induced current, equal to one-half of the propulsion current, flows.

This local circuit comprises the winding 15, the winding 13, a section of the trolley conductor 1, the trolley pole 32*, the train 30, a portion of the track circuit 2, and

the rail bond 19. As mentioned above, onehalf-of the propulsion current flows also through the windings 21 and 20*. In consequence thereof, a current represented by the dot-and-dash arrows 33 and having a value that is equal to the second portion of the propulsion current but flowing in an opposite direction thereto, is induced in a local circuit-Which comprises a winding 15, a winding 13",.a section of the trolley conductor 1, the trolley pole32, the train 30, a section ofthe track circuit 2 and a rail bond 19. 4

Since the induced currents flowing through the windings 15 and 13 are equal and opposite to the induced currents flowing in the windings 15 and 13", the said currents traversing, in opposite directions to the load 30, that portion of the trolley conductor '1 included in the railway section occupied by the load 30 neutralize the separate inductive effects that are impressed upon the telephone conductor 5. Again, theinductive effects arising from the-propulsion current flowing along that portion of the trolley conductor 1 extending'between the point A and the trolley pole '32 are neutralized by the inductive effects arising from the portion of the return propulsion current flowing along that portion of the feeder extending intermediate the two groups of transformers. or the entire length of the railway section in which the load 30 is situated. As a result of the aforementioned distribution of the currents, the inductive disturbances impressed upon the telephone circuit 5 are negligible, since the induced electromotive forces are substantially neutralized.

While the three transformers 14, 16 and 22 of Fig. 1 are shown for simplicity of :illustration as having separate core members,

I prefer to embody all of-the transformer windings comprising the aforesaid transformers in a single unitary structure that is represented in Fig. 3. The transformer 16 of Fig. 1, which comprises the coils 15 and 21, which carry current in common with the windings of both transformers 22 and 14, is, therefore, centrally disposed on the core leg 34 of a magnetizable core member 35. The coils 21 and 15 have two of their terminals connected to form a common lead 36. The coil 20" of the transformer 22, in combination with the coil 13*, is disposed on one side of the coils 21 and 15 but separated therefrom by means of magnetic shunts 37. Similarly, the coils 20 and 13 of the transformer 14 are placed on the other side of the coils 21 and 15 but separated therefrom by means of magnetic shunt-s 37 The coils 20 and 20 are connected to a,common conductor 38 which, in turn, is connected to one of the remaining terminals 39 of the coil 21. The coils 13 and 13 are likewise connected to a common conductor 40 which, in turn, is connected to a terminal 41 of the lntermediate coil 15. Leads 42 and 43 extendfrom paths for leakage flux, thereby magnetically segregating the three pairs of transformer coils from one another. At the same time,

the three pairs of coils are disposed upon a common core member by means of which the windings maybe installed without requiring undue space. I

In order to show the effectiveness of my transformer in preventing the flow of power currents in any one. rail-way section other than the one occupied by the load, it may be assumed that a locomotive 46 occupies a position on the railway at the right of the transformer windings 15' and 21 The power currents supplied to the locomotive 46 traverse theprimary windings 11 and 11 of the series transformers 10 of Fig. 1, in preference to being shunted around these windings through the'transformer coils13 and 13*, and 13 and 13. If the power currents tended to flow through the windings 13, 13",

however, to the return feeder 4 since the primary windings 11 and 11 are closely inductively linked with the secondary windings respectively associated therewith and connected in series in the return feeder 4. The power currents are also substantially pre-' eluded from flowing through the transformer windings located at the ends of the separate sections because of the high impedance between the series-connected windings, such as 13 and 15, 13 and 15, 13 and 15'', 13 and 15", relative to thelow-impedance path offered through the primary windings of the series transformers, such as 10.

By referring to the transformer of Fig. 3, it will be noted that the windings 13 and 13 are not closely mutually inductively related since magnetic shunts 37 are interposed therebetween. Of course, the same conditions hold with respect to the windings 13 and As a result, the path including windlngs 13 and 13 in series relation. is a very high-impedance path and the trolley currents will not flow through this path 46 will be fed thereto through the trolley conductor land the primary windings of the spaced series transformers 10. In this manner, the electromotive forces impressed upon the telephone conductor 5 may be neutralized, since the power currents are confined to definite paths. 1

The power currents are thus confined to the trolley conductor and the return feeder only, except in those sections in which the loads are located where the power currents may traverse the track circuit. The currents are prevented from flowing through the track circuit and ground, except in those sections in which the loads obtain. The currents traversing the track section of the occupied railway section, do not impress any serious disturbances on the adjacent telephone circuit because the inductive efi'ects arising therefrom are substantially neutralized, as explained above. Of course, while the description has been limited to the conditions obtaining when the load occupies a central position on a railway section, the conditions obtaining when the load occupies other positions can be readily deduced since the currents will divide in. proportion to the relative impedances of the several paths offered for the flow of the currents in the local circuits established through the load and the transformers located at the ends of the section in which the load obtains temporarily.

While I have shown and described, in detail, one embodiment of my invention, it will be understood by those'skilled in the art that other modifications may be made. therein without departing from the spirit and scope of the appended claims.

' I .claimas my invention:

1. A transformer comprisin a common core member, a plurality of coil-groups in eluding a middle coil-group thereon, said coil-groups severally comprising an inducing and an induced winding, magnetic shunts interposed between the coil-groups, a tap extending between the inducing and induced windings of the middle coil-group, and con- 88 nectors for connecting all of the inducing windings, together and for connecting all of the induced windings together.

2. A transformer comprising a common core member, a plurality of coil-groups including a middle coil-group thereon, said coil-groups severally comprising an inducing and an induced winding, a tap extending between the inducing and induced windings of the middle coil-group, connectors for connecting all of the inducing windings together, and for connecting all the induced windings together, and magnetic shunts interposed between the several inducing windings.

3. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, inductively related windings connected in series with the trolley conductor and the return feeder for interlinking themwith each other and fordividing the system into a plurality of adjacent sections, and a transformer having a plurality of inducing and inducedwindings connected respectively v between the return feeder and the track circuit and the trolley conductor and the track circuit, at least one inducing winding and one induced winding of the transformer being common to two adjacent railway sections.

4. An electric railway system comprising a trolley conductor, a return feeder therefor,

a track circuit, inductively related windings connected in series with the trolley conductor and the return feeder for interlinking them with each other and for'dividing the system into a plurality of adjacent sections, and a transformer having itsinducing and induced windings connected, respectively, between the return feeder and the track circuit and the trolley conductor and the track circuit, two inducing windings thereof being connected in parallel and to opposite terminals of said inductive winding that is con nected in series with the feeder conductor, and a .third being connected in series with said parallel-connected windings for connecting them to the track circuit, the induced windings of the transformer being correspondin ly arranged with respect to the trolley con uctor and the track. circuit and the other inductive winding that is connected in series with the trolley conductor.

- In testimony whereof I have hereunto subscribed my name this 26th day of Feb., 1916.

" CHARLES F. SCOTT. 

